The effective dynamic ranges of standard automated perimetry sizes III and V and motion and matrix perimetry.

OBJECTIVES

To establish the associations between threshold estimates of 4 perimetric tests and to define and compare the tests' effective dynamic ranges.

METHODS

We examined 152 patients with glaucoma and 80 controls using standard automated perimetry (SAP) with stimulus size III, SAP with size V, and motion and matrix perimetry. We explored the intertest associations using principal-components analysis. We defined the effective dynamic range bottom using the frequency of 0-dB trials on retest. We defined the upper effective dynamic range as a value above which fewer than 0.5% of the values fall in the controls. We also calculated the number of discriminable steps from normal to the floor value of the perimeter.

RESULTS

The association between SAP III and V was approximately linear up to a sensitivity of about 20 dB on both tests and with motion and matrix perimetry up to about 25 dB from 0 dB. While the upper bounds were similar among the tests, size V SAP had a lower floor and more discriminable steps.

CONCLUSIONS

The effective dynamic range of SAP III is substantially less than its physically tested limits. Size V stimuli have a greater effective dynamic range than size III by about 1 log unit and have about twice as many discriminable steps.